Burn Behavior... what changed?

[bwells794]

I have been burning Liberty Bricks in my stove exclusively this winter and the stove was brand new in the box when i bought it this past summer. At the beginning of the season, I started with a fresh pallet of bricks stored inside of my house. I would only burn 7 at most on a cold start as they packed a huge punch. Everything was going well, but now half way through my second pallet of bricks which is stored outside in the garage, the burn is completely different. I am not doing anything different in terms of loading, or air control, but even with upwards of 8 or 9 bricks, i have to leave the air control wide open to reach cruising temperatures that heat the space. If i damp as i used to, gradually working my way down to a low air setting, I will never break 400F and i have no idea why. This is also translating to shorter burn times with the same amount of fuel since I have to leave the air open longer to get up to temp.

Could there be any difference in this batch of bricks? They're stored out in the cold, but they're inside the garage so they haven't gotten wet. I bring in 2 or 3 packs at a time and they all behave the same so i doubt it has anything to do with the temperature of the block. this is absolutely puzzling to me as most problems i see on here are of runaway fires that get too hot.

if it matters, I have noticed that the secondaries on the right (your right when looking at it) dont seem to fire but middle and left look fine. the fire just all in all seems lazy unless the air control is open 3/4 to full. I don't have the recirculating fan, dryer, range hood or anything else running and the stove didnt behave like this in December. Is there ANYTHING at all you pro's out there might think i could check to put some pep back in it's step? I dont want to burn way more bricks than i have to just to keep the stove between 450-500F. At that level of inefficiency, i might as well turn the heat pump back on.

 

[begreen]

When was the last time the flue was cleaned? Is there a screen on the cap and if yes, was it too cleaned completely?

 

[bwells794]

The actual fireplace flue was was cleaned by a professional sweep back in the summer right before we installed a brand new SS liner (6"). Since then, it hasnt been swept. I would have to go up and look down it to see what it looks like but i would imagine that burning bricks with super low moisture content that i shouldnt have a creosote problem after only 2.5 months of burning would I? at least nothing so restrictive that i would see a behavior change this noticeable? there is plenty of draft. Fire starts right on up, zero problems.

 

[begreen]

I understand your thinking but in order to figure out what is wrong, eliminate variables. Start from the top down. Check the cap screen. It should be clean, but a cold chimney can cause accumulation. Even dry fuel bricks have some moisture content. Is the liner in an exterior chimney? Is it an insulated liner?

Also, has the top ever been off of this stove?

 

[Woody Stover]

Check the cap screen. It should be clean, but a cold chimney can cause accumulation.

Yep, it may look clean from the ground, but still have enough gunk on it to impact the draft. Also, what is the stack height? Some of the Jotuls need a fairly robust draft to work well...not sure if your model is one of those. If so, and your stack height is near the minimum required, a small amount of reduction of draft could have a big effect on how the stove runs.

 

[begreen]

It seems to be a fairly easy stove for draft. The F3CB worked ok for us on a 12ft chimney.

 

[mellow]

I would take a couple packs and open them up and leave them close to the stove for a few days then try them to see if there is a difference in the way they burn. You could try sticking a moisture meter in them to see what it reads.

I leave mine outside on my porch with a tarp covering them, I haven't seen any issues with them yet, I do see moisture on the inside of the packaging but they still light right up.

 

[bwells794]

update: hopped up on the roof and checked out the inside of the liner. other than a coating of soot, the liner looked great. i went ahead and swept it anyway. so i go back inside, remove the stove lid, and commence to vacuuming the whole thing. underside of the lid, on and around the baffle, in the firebox and even ran the hose end over the secondaries just in case and they all whistled. checked all the gaskets, basically just gave her a checkup. Everything looked good so i put her back together and started a fire. I don't know what made the difference, but she seems to be back to her old self... we'll see how this burn finishes out. Currently at 504 and climbing.

 

[begreen]

Has the top ever been off of this stove prior to today?

 

[bwells794]

yes, the top has to be removed to install. other than the install, no.

Also, the poor burn behavior continued shortly after my last update. I'm chalking this one up to either a bad batch of bricks, or keeping them outside negatively effecting them.

Lastly, to my previous point, as the flames were calming down, i saw ever so faint hints of green in the flames. While the flame was primarily blue and red, the green was unmistakable. A quick web search generally attributes this to copper? FWIW, these bricks dont look as "pretty" as the ones from the last batch either. sizes are also very inconsistent. I think the supplier may have just gotten lazy.

 

[blades]

Raw material mix changed- or some other variable in mfg. happens all the time with the pellet guys.

 

[bwells794]

So you're saying that the sawdust that comprises these bricks could have originated from a different species of tree thus behaving differently when burned?

 

[blades]

Yes, Actually it mostly a mix of different species. Making good blocks or pellets is a bit of an art- machinery not withstanding. The conifers make hotter pellets/ blocks due to the higher resin content - compression is the same. In addition depending on the mfg they may be adding a binding agent. The ideal situation is to be able to use the conifers in conjunction with deciduous at x ratio to eliminate the addition of a binding agent in a perfect world. That is not to say that some various processed/ engineered scrap may not find its way into the mix as well.

 

[begreen]

The reason I asked about the top being removed is that the F3CB lid is a little tricky due to the small allen screws that hold it in place. If not correctly aligned the screw can get under the lid edge instead of in its tapped hole. This leads to a lid being askew. This won't be apparent from the front but will show up when looked at on the side. The lid should be perfectly parallel with the body.



Or it could be bad bricks. Usually they have decent quality control, but maybe someone was rushing to get out for a Friday beer when your batch was made. I'd get in touch with the manufacturer and ask if they've been getting reports of bad bricks. Maybe send in a couple to them for testing? Copper could indicate contamination. Perhaps some construction scrap made it into this batch?

 

[bwells794]

Ah, I see what you're saying about the lid. Nope, its on correctly. At this point, I'm positive it's the bricks. Over the (cold) weekend, I had varying levels of performance and paid attention the bricks themselves as i loaded them. Some are way more dense than others and appear to not have been pressed with as much force and you can almost see the individual pieces of wood on the smaller faces which faintly resembles the appearance of pressoboard.

Here's what I have deduced: the first pallet of bricks was purchased in late August early September. Still very warm here that time of year and probably very little demand for the bricks which equates to higher inventory and most likely use of more sawdust and higher compression in each brick to consume the excess byproduct of this particular sawmill. Then by november, nights were starting to get chilly and bricks were probably flying off the lot causing less material to go into each brick to keep up with volume demands and if you press a smaller amount of sawdust with the same force as the bricks manufactured in the summer, the end result would be a substantially smaller brick which does not resemble the advertised product.

tl;dr: buy your bricks in the summer. lol or maybe i just way overthought that.

 

[begreen]

I would think that the brick die would determine the brick size. What could vary would be the degree of compression used to make the bricks and the material in them. If the brick size differed then maybe they came from a different plant or manufacturer?

 

[bwells794]

I would think that the brick die would determine the brick size. What could vary would be the degree of compression used to make the bricks and the material in them. If the brick size differed then maybe they came from a different plant or manufacturer?

no, liberty bricks is a small outfit about 20 min from my house. They are the mfg and you pick up on site. there is no delivery or retailer. The actual property is a sawmill but they run a side business where they have the machinery that they feed their byproducts from the mill into and presses them and feeds them out onto a conveyor belt where he wraps them in packs of ten. the whole operation is in plain view when you go to pick up the product. the machine has a sort of hopper that he feeds the sawdust into so he could control the amount of material in each brick. there has to be a variable somewhere in the equation because not all of the bricks are identical in weight or size. some are not even close, in fact.

 

[BrotherBart]

I have run into the same thing with the Liberty Bricks I am trying for the first time this season. Mine are all from the same pallet. I suspect moisture in some of the bricks but just went back to hardwood for this cold snap. I need to remember to bust a few of the bricks and get a moisture reading from them.

 

[begreen]

 

[BrotherBart]

I am going to weigh a bunch of them looking for differences. All that I have weighed before were amazingly consistent at 2.08 pounds apiece.

They say in their advertising that content will vary.

 

[nola mike]

I've kept mine in a shed all winter, as I have in the past (almost gone through them, I'll need to pick up another 1/2 ton I think). When they get wet, it's pretty obvious; they puff up and will never burn right, even if you dry them back out. Definitely get a different batch and run them back to back with your current bricks. I'd be curious as to the results. I've found them to be very consistent in 4 years of burning them. I've weighed mine differently, but get 22# per bundle.

 

[bwells794]

glad I'm not the only one. I don't think I'm going to get another pallet this season. I have about a weeks worth left. I'm too afraid I'll get another lame pallet. What I'll do next year is just get 2 pallets at the end of summer when the quality seems to be a little better and store them inside the house.

 

[nola mike]

Why not just bring a few back? Or if you want, I'll trade you a package (I'm in the museum district). I'm more curious than anything else.

 

[mellow]

I am mixing mine (not liberty) with wood and having great success, I can fit the bricks in the corners and on top of the wood and stretch out my burn times. I didn't like just burning the bricks alone as they turn to mush and it was hard to stack on top of old ones and keep the fire going, with the wood leaving hard coals behind I could get the fire going again faster.

 

[begreen]

They won't know unless the customer tells them about the differences you are noting.